Is a degree holder graphic designer preferred by the employer over those who are experienced non degree holders?

Not really..
I am more than 9 years experienced in the art field.
I do not have such degree.
I got all the opportunities based on my portfolio and skills.
When I became TL - I was working with BFAs and Non-BFAs in my team.
I noticed that the Non BFAs were more talented and hardworking than the BFAs as they knew who their competitors were.